Stucco is sometimes removed from a building to
determine if proper flashing was installed, replace leaky windows, repair water
damaged wood framing members or other reasons that would require the removal of
the stucco around windows. It is possible to patch and restore the stucco
membrane. Removal procedures can vary depending on the substrate, framing and
overall remediation plans. The following outlined procedure is for removal and
replacement of cement stucco around windows on wood framed walls.
It is important to determine the expectations of the
building owner and inform them of the finishing options. The finishing options
to the repairs around windows depending on the degree or desire of finish
appearance and should be discussed prior to the start of work. The following
will help with some decisions, options and help clear up confusion for all
parties involved.
A comprehensive evaluation of the exterior plaster should be
conducted by qualified persons prior to making any decisions for final scope of
repairs. An important item needed to determine the full scope of stucco repairs
is the type of finish coat (acrylic or cement) on the building and the overall
condition of the walls. Has the building been painted and what type of paint was
used? Buildings with elastomeric type paints will limit the options of repairs.
Stucco Removal
Stucco removal can be very dusty; protective clothing, eye
protection, and a respirator are always recommended. The removal of stucco is
best done by cutting the stucco with a power saw using a masonry blade. Vertical cuts may be further away from the
window as they should reach the next framing member (stud). Once the saw cuts
are complete, a cold chisel can be placed into the saw cut and used to break or
fracture the last remaining uncut thickness of plaster. The stucco can then be
pulled off the wall with minimal damage to the underlying WR membrane. For
large areas of removal, it is suggested to cut the stucco into squares that can
be easily handled.
In some rare cases the WR membrane may be adhered to the
back of the stucco. In these instances it will be necessary to remove the
stucco back to point where the stucco is not bonded the WR membrane. The cut
stucco edge will be straight and smooth, it is recommended the edges be jagged
and rough. This will produce a better key (bond) between the new patch and
existing stucco and can minimize the chance for a separation crack. A hammer
can be used to chip away small sections, leaving some of the metal lath exposed
if possible.
The WR membrane should be peeled back carefully to minimize
tears, holes or other damage to the WR membrane. It is necessary to leave some
existing WR membrane for proper lap and integration with flashings. A minimum
two-inch over lap on horizontal joints and a six-inch overlap on vertical
joints of the WR membrane will be needed when final lathing takes place.
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